U.S. Pat. No. 4,161,984 discloses a locking device that is used to support equipment in the production string of an oil and/or gas well which is particularly suitable for use in a well which may be subject to high pressures either above or below the lock. However, that lock utilizes a locator key which is urged outwardly by a spring whereby the locator key may be fully extended when the lock is locked allowing an to accumulate between the inside of the key and the housing causing difficulty in retracting the key and the lock when the lock is being removed.
The improved lock of the present invention insures that locking dogs will positively hold upwardly or downwardly loads on the lock without relying upon the locator keys and the locator keys are held in a retracted position when the lock is set thereby avoiding accumulation of debris behind the locator keys which would prevent their retraction and the removal of the lock.